Since its inception in Roman Catholic Spain in the 1940s, the Cursillo movement has been a steadily-growing phenomenon and has spread into many Protestant churches worldwide under various names. The weekend initiation is often a deeply-felt experience that boasts of many conversions and recommitments. Yet in this comprehensive analysis of Cursillo the author finds theological concerns, questions about the propriety of the methods, and complications such as disaffection from the local church, transfer of loyalty to the Cursillo community, and a significant drop-out rate, raising implications for similar, spiritual movements. Interviews with former Cursillo participants confirmed many of these conclusions but also raised a challenge to the church: many Cursillo participants do not perceive vital faith in their local church. The author suggests that the Cursillo attempts to imitate the work of the church in an extraordinary form and that this might initiate some of the unhelpful results. The church would be better served by seeking to revitalize its ordinary ministries of Word and sacrament, prayer, community, and Sabbath observance.